Sodium (Na)

Sodium (Na)

Test: In vitro test for the quantitative determination of sodium
Submission Criteria:

Specimen: Serum (preferred) or Plasma: Li-heparin only

Minimum Volume: 2 mL

Container: Gold-top tube

Storage and Stability: Unseparated from cells:          2 hours

Separated from cells:                   14 days at 15-25ºC

14 days at 2-8ºC

365 days at -20º

Rejection Criteria: Rejection criteria include but are not limited to:

  1. Specimen containing fibrin or clots.
  2. Hemolyzed specimens
  3. Excessive platelet clumping
  4. Leaking specimens
  5. Substandard mixing or collection
  6. Expired or improperly stored collection tubes
  7. Improperly filled tubes based on collection tube manufacture’s guidelines.
  8. Contaminated specimens (IV fluid, foreign particles, etc.)
  9. Specimens not analyzed within the appropriate time frame.
  10. Samples not shipped at appropriate temperature. Samples without two proper identifiers or samples having identifiers that do not match the electronic or paper lab requisition.
Turnaround Time: 1 days
Clinical Significance: Sodium is the major extracellular cation and functions to maintain fluid distribution and osmotic pressure. Some causes of decreased levels of sodium include prolonged vomiting or diarrhea, diminished reabsorption in the kidney and excessive fluid retention. Common causes of increased sodium include excessive fluid loss, high salt intake, and increased kidney reabsorption.
Reference Ranges:
Normal: 135-145 mmol/L
Critical Value: ≤ 120 mmol/L and ≥ 160 mmol/L
Method: Ion-Selective Electrode (ISE) makes use of the unique properties of certain membrane materials develop an electrical potential (electromotive force, EMF) for the measurement of ions in solution.

Roche/Hitachi Cobas ISE